1. Field of the Invention
The present invention relates to a method of machining a diamond plate or block using a laser beam, after a metallic membrane or layer has been deposited on the surface of the diamond plate or block.
2. Description of the Related Art
As diamond is the hardest known material and has a high resistance to abrasion, the machining, i.e., cutting and/or engraving, thereof is very difficult compared to the machining of other gem-stones or hard metals. Diamond, however, has a relatively weaker plane oriented in a certain direction, and thus a rough diamond can be split to a desired size by a cleaving process in which the rough diamond is divided along the cleavage plane.
As an alternative to the cleaving process, diamond can be cut by a sawing process using a saw blade rotated at a high speed while being supplied with diamond powder onto the surface thereof, or by using a steel wire assisted by diamond powder (wire-cutting).
Nevertheless, it is extremely difficult to machine, in particular, a diamond plate, due to the brittleness and hardness thereof. Currently, the only known process by which this can be accomplished is a creep-feed grinding, but in this process, the in-feed of the tool must be set to a minimum rate.
The above conventional processes, however, have the following drawbacks:
The cleaving of a diamond block requires great skill and a very experienced operator. Nevertheless, a portion along which it is desired to split the diamond block is sometimes different from that which can be split, or it is difficult to accurately forecast which portion will be split. The sawing process using a saw blade or a steel wire is liable to damage the diamond workpiece, because of the hardness and the brittleness of the workpiece, and requires a very long processing time. The creep-feed grinding processing of a diamond plate also requires a very long processing time, because the in-feed of the tool must be at a minimum rate. Further, the reliability of this process is not high.
Further, a diamond workpiece, regardless of whether it is a block or a plate, is easily cracked and splintered during the machining process. It is widely known in this field that the diamond workpiece rarely can be normally cut, and even when the diamond workpiece can be cut, a large amount of waste occurs due to cracks and splinters generated during the process, which greatly increases the processing costs.
Currently laser beam machining is widely utilized in many fields, but this technique has not been utilized in diamond processing, because it causes the generation of a larger amount of cracks and splinters.